Light-emitting device

ABSTRACT

A light-emitting device includes: a laser light source that radiates blue-based light as primary light; a wavelength converting member that emits secondary light, the secondary light including wavelength-converted light, the wavelength-converted light being the primary light converted into light having more long-wavelength components than the primary light; a first light-guiding member that transmits the secondary light emitted by the wavelength converting member; and a second light-guiding member which includes a resin material, and transmits the secondary light transmitted by the first light-guiding member, and the first light-guiding member and the second light-guiding member are connected by a connector, the connector including a numerical aperture (NA) converting member that optically connects a transmission path in the first light-guiding member and a transmission path in the second light-guiding member.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority of Japanese PatentApplication Number 2019-215034, filed on Nov. 28, 2019, the entirecontent of which is hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to a light-emitting device.

BACKGROUND ART

Conventionally, light-emitting devices each including a plurality ofoptical fibers that are flexible and guide excitation light emitted froma plurality of excitation light sources, a multimode fiber that guidesthe excitation light guided through the plurality of optical fibers, anda light-emitting unit that emits fluorescence by receiving theexcitation light guided through the multimode fiber have been disclosed.

CITATION LIST Patent Literature

[PTL 1] Japanese Patent No. 6161877

SUMMARY Technical Problem

Optical fibers and multimode fibers in conventional light-emittingdevices usually include glass fiber yarn. This makes the conventionallight-emitting devices expensive, and thus a reduction in costs isdesired. For this reason, the use of inexpensive resin materials such asplastic for the optical fibers and the multimode fibers can becontemplated. However, such a resin material cannot tolerate heatproduced by heat generation sources, such as excitation light sources,and this makes it difficult to apply such a resin material tolight-emitting devices.

In view of the above, the present disclosure aims to provide alight-emitting device that can reduce an effect of heat produced by aheat generation source while reducing a rise in cost.

Solution to Problem

A light-emitting device according to an aspect of the present disclosureincludes: a solid-state light-emitting element that radiates blue-basedlight as primary light; a wavelength converting member that emitssecondary light, the secondary light including wavelength-convertedlight, the wavelength-converted light being the primary light convertedinto light having more long-wavelength components than the primarylight; a first light-guiding member that transmits the secondary lightemitted by the wavelength converting member; and a second light-guidingmember which includes a resin material, and transmits the secondarylight transmitted by the first light-guiding member. The firstlight-guiding member and the second light-guiding member are connectedby a connector, the connector including a numerical aperture (NA)converting member that optically connects a transmission path in thefirst light-guiding member and a transmission path in the secondlight-guiding member.

It should be noted that this comprehensive or concrete aspect of thepresent disclosure may be realized by optionally combining a system, amethod, or an integrated circuit.

Advantageous Effect

A light-emitting device according to the present disclosure can reducean effect of heat produced by a heat generation source while reducing arise in cost.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures depict one or more implementations in accordance with thepresent teaching, by way of examples only, not by way of limitations. Inthe figures, like reference numerals refer to the same or similarelements.

FIG. 1 is a perspective view illustrating a lighting system for anendoscope which includes a light-emitting device according to anembodiment.

FIG. 2 is a block diagram illustrating the light-emitting deviceaccording to the embodiment.

FIG. 3 is diagram schematically illustrating the light-emitting device,a first light-guiding member, a connector, and a second light-guidingmember according to the embodiment.

FIG. 4 is a partially enlarged cross sectional view illustrating thefirst light-guiding member, the connector, and the second light-guidingmember according to the embodiment.

FIG. 5 is a diagram schematically illustrating a relationship betweenthe first light-guiding member, the connector, and the secondlight-guiding member according to the embodiment.

DETAILED DESCRIPTION

Hereinafter, embodiments according to the present disclosure will bedescribed with reference to the drawings. The embodiments describedbelow each show an example of the present disclosure. Therefore,numerical values, shapes, materials, structural elements, thearrangement and connection of the elements, etc. presented in theembodiments below are mere examples and do not limit the presentdisclosure. Furthermore, among the structural elements in theembodiments below, those not recited in any one of the independentclaims will be described as optional structural elements.

It should be noted that the drawings are schematic diagrams, and do notnecessarily provide strictly accurate illustrations. Throughout thedrawings, the same reference numeral is given to the same structuralcomponents.

Moreover, the embodiments described below use an expression such assubstantially plane-shaped. For example, substantially plane-shaped notonly means that which is perfectly plane-shaped, but also means thatwhich is practically plane-shaped. In addition, the substantiallyplane-shaped is considered as plane-shaped within the scope in which anadvantageous effect can be produced by the present disclosure. The sameapplies to other expressions using “substantially”.

Hereinafter, a light-emitting device according to an embodiment of thepresent disclosure will be described.

Embodiment

[Configuration: Light-Emitting Device 1]

FIG. 1 is a perspective view illustrating lighting system for endoscope100 which includes light-emitting device 1 according to an embodiment.

As illustrated in FIG. 1, light-emitting device 1 according to theembodiment is a reflective lighting device that uses laser light, andincluded in, for example, lighting system for endoscope 100 which isused for an endoscope. It should be noted that light-emitting device 1may be used for, for example, a downlight, a spotlight, and the like.Lighting system for endoscope 100 includes light-emitting device 1 andcamera control unit 110.

Laser light that light-emitting device 1 emits is blue-based light, forexample. Light-emitting device 1 emits laser light that is blue-basedlight and quasi-white secondary light that is produced by combining aportion of the absorbed laser light and green to yellowwavelength-converted light.

FIG. 2 is a block diagram illustrating light-emitting device 1 accordingto the embodiment. FIG. 3 is a diagram schematically illustratinglight-emitting device 1, first light-guiding member 50, connector 70,and second light-guiding member 60 according to the embodiment.

As illustrated in FIG. 2 and FIG. 3, light-emitting device 1 includesexcitation light source 3, first light-guiding member 50, secondlight-guiding member 60, and connector 70.

[Excitation Light Source 3]

Excitation light source 3 is a device that emits laser light. Excitationlight source 3 includes housing body 31, one or more laser light sources32, prism 33, condenser lens 34, first glass rod 35, wavelengthconverting member 36, second glass rod 37, heat sink 38, and drivecircuit 39.

Housing body 31 is a case of excitation light source 3. Housing body 31houses laser light source 32, prism 33, condenser lens 34, first glassrod 35, heat sink 38, and drive circuit 39. In addition, housing body 31holds wavelength converting member 36 such that wavelength convertingmember 36 is optically connectable with each of first glass rod 35 andsecond glass rod 37.

Laser light source 32 is a solid-state light-emitting element thatradiates laser light as primary light, and emits substantiallycollimated laser light. Laser light source 32 is attached to asubstrate, and is thermally connected to heat sink 38 via the substrate.In this embodiment, excitation light source 3 uses a plurality of laserlight sources 32, and the plurality of laser light sources 32 areconsidered as one set. Each of the one set of laser light sources 32emits laser light, and the laser light is caused to enter wavelengthconverting member 36 via prism 33 and first glass rod 35.

It should be noted that although a plurality of laser light sources 32(e.g. four or eight laser light sources 32) are used in this embodiment,only one laser light source 32 may be used. Laser light that laser lightsource 32 emits in this embodiment is light having a predeterminedwavelength within a wavelength band of blue-based light that includespurple to blue.

Laser light that laser light source 32 emits in this embodiment has across-sectional shape that is oval and 1 mm×4 mm in size. In addition,energy distribution of the laser light is in accordance with theGaussian distribution.

In addition, although the one set of laser light sources 32 is used inthis embodiment, a plurality of sets of laser light sources 32 may beused. In this case, prism 33 and condenser lens 34 may be provided as apair corresponding to each set of laser light sources 32.

Although laser light source 32 is a semiconductor laser which is, forexample, an InGaN-based laser diode, laser light source 32 may be asemiconductor laser that emits light in a different wavelength (otherthan the wavelength band of blue-based light) or a light emitting diode(LED), so long as light emitted can excite wavelength converting member36.

In addition, laser light source 32 outputs laser light under the controlof drive circuit 39. That is, laser light source 32 emits a desiredlaser light under the control of drive circuit 39.

Prism 33 is disposed in housing body 31 such that laser light emitted bythe one set of laser light sources 32 is guided to condenser lens 34 tobe condensed onto condenser lens 34. That is, prism 33 condenses thelaser light emitted from laser light sources 32 so that the condensedlaser light enters condenser lens 34. Prism 33 is, for example, arhomboid prism, a polarizing mirror, etc.

Condenser lens 34 is disposed in housing body 31 so as to be locatedopposite prism 33. Condenser lens 34 further condenses the laser lightexited from prism 33, and causes the laser light to enter first glassrod 35. It should be noted that condenser lens 34 is a spherical lens oran aspheric lens, but condenser lens 34 need not be the lenses indicatedabove so long as condenser lens 34 is an optical device that cancondense laser light and can cause the laser light to enter first glassrod 35.

First glass rod 35 is disposed in housing body 31 so as to be locatedopposite condenser lens 34. First glass rod 35 is a light pipe thatincludes glass as a base material and has the inner surface that iscoated with a dielectric multilayer so as to highly efficiently reflectlaser light that is condensed by and exited from condenser lens 34. Itshould be noted that first glass rod 35 may be a light pipe having ametallically-coated surface inside so as to highly efficiently reflectthe laser light.

First glass rod 35 constitutes a transmission path that transmits thelaser light condensed by and exited from condenser lens 34. First glassrod 35 mixes the laser light by causing the laser light to repeatedlyreflect inside while the laser light is guided through first glass rod35 to even out the Gaussian distribution. That is, tophat laser lightwhose peak portion is smoothed (substantially evened out) is caused toexit from first glass rod 35. First glass rod 35 emits laser light thatis mixed, and causes the mixed laser light to enter wavelengthconverting member 36.

When the transmission path in first glass rod 35 is cut on a plane thatis perpendicular to a direction in which the laser light transmits, across section of the transmission path is polygonally shaped. In thisembodiment, a cross section of the transmission path is quadrilaterallyshaped.

Wavelength converting member 36 includes phosphor (wavelength convertingelement) that converts the laser light that is mixed by first glass rod35 into wavelength-converted light (fluorescence). That is, wavelengthconverting member 36 performs wavelength conversion on laser lightentered from a first glass rod 35-side face, and emits secondary lightthat includes wavelength-converted light on which the wavelengthconversion is performed from the opposite face (second glass rod 37-sideface). Specifically, wavelength converting member 36 emits secondarylight that includes laser light as primary light andwavelength-converted light that is the laser light as primary lightconverted into light having more long-wavelength components than theprimary light (the proportion of the long-wavelength component is high),and causes the secondary light to enter second glass rod 37.

In addition, tophat laser light enters wavelength converting member 36.Accordingly, wavelength converting member 36 emits secondary lighthaving reduced luminance irregularity in which only a portion ofwavelength converting member 36 is brightly illuminated.

In wavelength converting member 36, the phosphor is dispersed in abinder that is a transparent material including ceramic such as glass,silicone resin, or the like. The phosphor is, for example, multicolorphosphor such as ZnO, an yttrium aluminum garnet (YAG)-based phosphor, aCASN-based phosphor, a SCASN-based phosphor, or a barium, magnesium,aluminum (BAM)-based phosphor, and is selected as appropriate accordingto a type of laser light. It should be noted that the binder is notlimited to include ceramic, silicone resin, or the like, and othertransparent materials such as transparent glass, or the like, may beused.

In addition, the phosphor may be a red phosphor, a green phosphor, ablue phosphor, etc., and wavelength-converted light, such as red light,green light, and blue light, may be emitted according to the laserlight. In this case, these red, green, and blue wavelength-convertedlights may be combined to produce white light. In this embodiment, thephosphor emits quasi-white secondary light.

In addition, wavelength converting member 36 is a flat plate-shapedstructure in which a phosphor layer etc. are disposed on a sapphiresubstrate, for example. Wavelength converting member 36 is fixed tohousing body 31 in a state in which wavelength converting member 36 isin contact with housing body 31. That is, wavelength converting member36 dissipates heat produced in the phosphor by causing housing body 31to function as heat sink 38.

Second glass rod 37 is fixed to housing body 31, and optically connectswavelength converting member 36 and first light-guiding member 50.Second glass rod 37 is disposed so as to be located opposite wavelengthconverting member 36. Second glass rod 37 is a light pipe that includesglass as a base material, and has the inner surface that is coated witha dielectric multilayer so as to highly efficiently reflect secondarylight that is exited from wavelength converting member 36. It should benoted that second glass rod 37 may be a light pipe having ametallically-coated surface inside so as to highly efficiently reflectthe secondary light.

It should be noted that second glass rod 37 may have the sameconfiguration as first glass rod 35, but second glass rod 37 may beprovided with a reflective film inside which enhances transmissionefficiency of white light.

Second glass rod 37 constitutes a transmission path that transmitssecondary light including wavelength-converted light whose wavelength isconverted and which is emitted by wavelength converting member 36.Second glass rod 37 causes the secondary light to repeatedly reflectinside while the secondary light is guided through second glass rod 37.Second glass rod 37 mixes the secondary light while the secondary lightis guided through second glass rod 37 to emit secondary light whoseGaussian distribution is evened out. That is, second glass rod 37 emitstophat secondary light whose peak portion is smoothed. Second glass rod37 emits the mixed secondary light, and causes the mixed secondary lightto enter first light-guiding member 50.

When the transmission path in second glass rod 37 is cut on a plane thatis perpendicular to a direction in which the secondary light transmits,a cross section of the transmission path is polygonally shaped. In thisembodiment, second glass rod 37 has the transmission path whose crosssection is quadrilaterally shaped.

Heat sink 38 is a heat dissipation member for dissipating heat producedin laser light sources 32, and includes a plurality of fins. Inaddition, the substrate to which laser light sources 32 are attached isfixed by heat sink 38.

Drive circuit 39 is electrically connected with an electric power systemvia an electric power line etc., and supplies electric power to eachlaser light source 32. In addition, laser light sources 32 output laserlight under the control of drive circuit 39 such that laser lightsources 32 emit predetermined laser light.

Drive circuit 39 may have a function of modulating laser light thatlaser light sources 32 emit. In addition, drive circuit 39 may include,for example, an oscillator that drives laser light sources 32 based on apulse signal.

[First Light-Guiding Member 50]

First light-guiding member 50 is an optical fiber cable that transmitssecondary light exited from wavelength converting member 36. Firstlight-guiding member 50 has a dual structure in which a core having ahigh refractive index is surrounded with a clad layer having arefractive index lower than that of the core, and includes a claddingthat covers the clad layer, for example. It should be noted that whenlight-emitting device 1 includes a plurality of sets of laser lightsources 32, a plurality of first light-guiding members 50 may also beprovided.

First light-guiding member 50 includes a material, such as glass havinghigh heat resistance or resin having excellent heat resistance. Thisenables laser light exited from second glass rod 37 to enter firstlight-guiding member 50.

In the embodiment, first light-guiding member 50 is a bundle fiberconsists of multi-component glass fibers each of which is approximately25 μm to 50 μm in diameter and which are bundled together and bondedwith adhesive. In addition, in this embodiment, the diameter of firstlight-guiding member 50 is approximately 0.1 mm to 0.4 mm, and thenumerical aperture of first light-guiding member 50 is 0.8 to 0.9.

First light-guiding member 50 has one end on a second glass rod 37 sidewhich is optically connected with and fixed to second glass rod 37 andfrom which secondary light exited from wavelength converting member 36enters. In addition, first light-guiding member 50 has the other endthat is on a side opposite the second glass rod 37 side, and isremovably fixed to connector 70.

Specifically, first light-guiding member 50 has entrance face 51 fromwhich secondary light enters, and exit face 52 from which the secondarylight entered from entrance face 51 and guided through firstlight-guiding member 50 exits.

Entrance face 51 is substantially plane-shaped and is one end face offirst light-guiding member 50. Entrance face 51 is disposed so as to belocated opposite second glass rod 37. First light-guiding member 50 isdisposed such that the central axis of entrance face 51 substantiallyaligns with the central axis of the transmission path in second glassrod 37. In addition, exit face 52 is substantially plane-shaped and isthe other end face of first light-guiding member 50. Exit face 62 isdisposed so as to be located opposite first light-guiding member 50 viaconnector 70.

FIG. 4 is a partially enlarged cross sectional view illustrating firstlight-guiding member 50, connector 70, and second light-guiding member60 according to the embodiment.

As illustrated in FIG. 4, first light-guiding member 50 includes, on theother end, connecting terminal 150 that is mechanically connected withconnector 70. Connecting terminal 150 includes ferrule 151, housing 154,flange 152, and spring 153.

Ferrule 151 includes zirconia, nickel, etc., and is an aligningcomponent that holds first light-guiding member 50 in a predeterminedorientation, for example. Ferrule 151 includes an insertion hole inwhich an end of first light-guiding member 50 is inserted. The end is ona side opposite a second glass rod 37 (excitation light source 3) side.The end of first light-guiding member 50 which is inserted in theinsertion hole is an end on a connector 70 side. In addition, whenconnecting terminal 150 is connected to connector 70, ferrule 151 isinserted in case 71 of connector 70, and is held so as to be locatedopposite numerical aperture (NA) converting member 73 of connector 70and adjacent to NA converting member 73. Accordingly, ferrule 151 holdsthe end of first light-guiding member 50 in such a manner that exit face52 of first light-guiding member 50 and NA converting member 73 face andare adjacent to each other. Ferrule 151 is an example of a firstferrule.

Housing 154 holds ferrule 151, and has a tubular shape that forms theoutline of connecting terminal 150. Housing 154 houses flange 152,spring 153, etc. Housing 154 is engaged with and fixed to connectionportion to be connected 71 a in case 71 of connector 70. In thisembodiment, a female screw portion is formed in housing 154, and a malescrew portion is formed in connection portion to be connected 71 a incase 71 of connector 70, and thus housing 154 is being screwed andcoupled to connection portion to be connected 71 a.

Flange 152 is held by housing 154 in a state in which flange 152 isconnected to one end portion of ferrule 151. In addition, flange 152receives stress from spring 153 by being connected to spring 153, andthis energizes ferrule 151 to a direction to which the stress isapplied.

Spring 153 is disposed between flange 152 and housing 154. Whenconnecting terminal 150 is connected to connector 70, spring 153energizes ferrule 151 toward an NA converting member 73 side via flange152. When housing 154 is coupled to connection portion to be connected71 a, spring 153 applies stress to flange 152 by being pushed by housing154, and presses ferrule 151 to the NA converting member 73 side.

It should be noted that the coupling of first light-guiding member 50and connector 70 is not limited to the above-described details. Theother end of first light-guiding member 50 may simply be fixed with afixing member such as a screw.

[Second Light-Guiding Member 60]

Second light-guiding member 60 is an optical fiber cable that transmitssecondary light exited from wavelength converting member 36. Secondlight-guiding member 60 has a dual structure in which a core having ahigh refractive index is surrounded with a clad layer having arefractive index lower than that of the core, and includes a claddingthat covers the clad layer, for example. It should be noted that whenlight-emitting device 1 includes a plurality of sets of laser lightsources 32, a plurality of second light-guiding members 60 may also beprovided.

Second light-guiding member 60 includes a material different from amaterial which first light-guiding member 50 includes. Secondlight-guiding member 60 includes, for example, a light-transmissiveresin material. In this embodiment, the diameter of second light-guidingmember 60 is 0.4 mm to 3 mm, and the numerical aperture of secondlight-guiding member 60 is 0.5 to 0.7.

FIG. 5 is a diagram schematically illustrating a relationship betweenfirst light-guiding member 50, connector 70, and second light-guidingmember 60 according to the embodiment.

As illustrated in FIG. 5, the transmission path of secondary light insecond light-guiding member 60 has diameter A2 that is greater thandiameter A1 of the transmission path of the secondary light in firstlight-guiding member 50. That is, the average diameter of secondlight-guiding member 60 is greater than the average diameter of firstlight-guiding member 50. Accordingly, entrance face 61 of secondlight-guiding member 60, which will be described later, is greater thanexit face 52 of first light-guiding member 50.

Although the area of exit face 52 of first light-guiding member 50 issmaller than that of entrance face 61 of second light-guiding member 60,first light-guiding member 50 has the numerical aperture greater thanthat of second light-guiding member 60. Accordingly, by making diameterA2 of entrance face 61 of second light-guiding member 60 greater thandiameter A1 of exit face 52 of first light-guiding member 50, thedecrease in light transmission efficiency at the time of opticallyconnecting first light-guiding member 50 and second light-guiding member60 is reduced, when first light-guiding member 50 and secondlight-guiding member 60 are optically connected with each other.

As illustrated in FIG. 4, second light-guiding member 60 has one endthat is on a first light-guiding member 50 side, and is removably fixedto connector 70. Second light-guiding member 60 is optically connectedwith first light-guiding member 50 via connector 70. Secondary lightthat is exited from wavelength converting member 36 and guided throughfirst light-guiding member 50 enters second light-guiding member 60.

Specifically, second light-guiding member 60 has entrance face 61 fromwhich the secondary light enters, and exit face 62 from which thesecondary light that is entered from entrance face 61 and guided throughsecond light-guiding member 60 exits.

Entrance face 61 is substantially plane-shaped, and is one end face ofsecond light-guiding member 60. Entrance face 61 is disposed so as to belocated opposite second glass rod 37. Second light-guiding member 60 maybe disposed such that the center of entrance face 61 is within thecentral axis of the transmission path in second glass rod 37, forexample. In addition, exit face 62 is substantially plane-shaped, and isthe other end face of second light-guiding member 60. Exit face 52 isdisposed so as to be located opposite second light-guiding member 60 viaconnector 70.

In addition, as illustrated in FIG. 5, second light-guiding member 60includes light distribution control structure 60 a that performs lightdistribution control on secondary light transmitted by firstlight-guiding member 50 before emitting the secondary light.

Light distribution control structure 60 a is disposed on the other endface of second light-guiding member 60. In this embodiment, lightdistribution control structure 60 a is integrally formed on the otherend face of second light-guiding member 60, and includes exit face 62 ofsecond light-guiding member 60. Light distribution control structure 60a in this embodiment is in a shape of a convex portion of ahemispherical shape.

An angle of radiation of secondary light that is exited from lightdistribution control structure 60 a is specified according to an angleof view of camera 116. That is, the numerical aperture of lightdistribution control structure 60 a is specified according to an angleof view of camera 116. An angle of radiation of the secondary light thatis exited from light distribution control structure 60 a may beequivalent to an angle of view of camera 116.

Light distribution control structure 60 a is obtained by melting theother end face of second light-guiding member 60 to form a curvedsurface having a desired curvature, or obtained by grinding the otherend face of second light-guiding member 60 to form a curved surfacehaving a desired curvature, for example. The curvature according to theembodiment is approximately 20 mm, for example.

It should be noted that light distribution control structure 60 a isintegrally formed with second light-guiding member 60, but lightdistribution control structure 60 a may be a member separated fromsecond light-guiding member 60. That is, light distribution controlstructure 60 a may be a convex lens, a concave lens, or the like. Inthis case, light distribution control structure 60 a is located oppositethe other end face of second light-guiding member 60, and is held in endportion 115 illustrated in FIG. 1 in an orientation in which lightdistribution control is to be performed on secondary light exited fromthe other end face of second light-guiding member 60.

In addition, second light-guiding member 60 includes, on the other end,connecting terminal 160 that is mechanically connected with connector70. Connecting terminal 160 includes ferrule 161, housing 164, flange162, and spring 163. Since connecting terminal 160 included in secondlight-guiding member 60 has the same configuration as connectingterminal 150 included in first light-guiding member 50 which includesferrule 151, housing 154, flange 152, and spring 153, descriptions offerrule 161, housing 164, flange 162, and spring 163 are omitted.Ferrule 161 is an example of a second ferrule.

[Connector 70]

Connector 70 is an optical connector that optically connects thetransmission path in first light-guiding member 50 and the transmissionpath in second light-guiding member 60 for converting the differencebetween the numerical aperture of first light-guiding member 50 and thenumerical aperture of second light-guiding member 60. Firstlight-guiding member 50 and second light-guiding member 60 havedifferent diameters and include different materials. Specifically,connector 70 optically connects connecting terminal 150 (the other endportion on an exit face 52 side of first light-guiding member 50) offirst light-guiding member 50 and connecting terminal 160 (one endportion on an exit face 62 side of second light-guiding member 60) ofsecond light-guiding member 60.

Connector 70 includes case 71, support portion 72, and NA convertingmember 73.

Case 71 has a tubular body shape having unclosed ends, and secondarylight passes through the inside of case 71. Case 71 includes one end andthe other end in which connection portion to be connected 71 a andconnection portion to be connected 71 b are formed, respectively. Firstlight-guiding member 50 that transmits secondary light is inserted inand connected to connection portion to be connected 71 a in the one endof case 71. Second light-guiding member 60 that transmits the secondarylight is inserted in and connected to connection portion to be connected71 b in the other end of case 71. Case 71 includes fixing members whichare attached to case 71 and support first light-guiding member 50 andsecond light-guiding member 60. In addition, connection portion to beconnected 71 a in the one end of case 71 has the same configuration asconnection portion to be connected 71 b in the other end of case 71.

Case 71 is light-transmissive. Case 71 includes a metal material, suchas aluminum, iron, or the like.

Support portion 72 is housed and held inside case 71, and supports NAconverting member 73. Support portion 72 holds NA converting member 73such that NA converting member 73 is oriented facing exit face 52 offirst light-guiding member 50 and entrance face 61 of secondlight-guiding member 60.

NA converting member 73 is a convex lens, a concave lens, a parabolamirror, or the like. NA converting member 73 is disposed in thetransmission path between first light-guiding member 50 and secondlight-guiding member 60. In other words, NA converting member 73 isdisposed between exit face 52 of first light-guiding member 50 andentrance face 61 of second light-guiding member 60.

Specifically, NA converting member 73 is supported by support portion 72of connector 70 in an orientation in which NA converting member 73causes secondary light exited from exit face 52 of first light-guidingmember 50 to enter entrance face 61 of second light-guiding member 60.NA converting member 73 is held inside support portion 72 such that thecentral axis of NA converting member 73 substantially aligns with thecentral axis of exit face 52 of first light-guiding member 50 and thecentral axis of entrance face 61 of second light-guiding member 60.

Since first light-guiding member 50 includes glass and secondlight-guiding member 60 includes a resin material in this embodiment,the embodiment has a characteristic in which the numerical aperture offirst light-guiding member 50 (angle of radiation of light exited fromfirst light-guiding member 50) is greater than the numerical aperture ofsecond light-guiding member 60 (angle of radiation of light exited fromsecond light-guiding member 60). In order to cause secondary lightguided to be reflected at an interface between the core and the cladlayer in second light-guiding member 60, NA converting member 73 causessecondary light that is exited from exit face 52 of first light-guidingmember 50 to be substantially collimated, and causes the substantiallycollimated secondary light to enter entrance face 61 of secondlight-guiding member 60.

[Camera Control Unit 110]

Camera control unit 110 is a unit that processes images imaged by camera116 provided in end portion 115. Camera control unit 110 includes, forexample, image processor 111, controller 112, and storage 113.

Although not illustrated, the other end of second light-guiding member60 and the other end of image transmission cable 117 are connected toend portion 115. Camera 116 that images a subject is included in endportion 115.

Camera 116 is, for example, a charge-coupled device (CCD) camera. Camera116 transmits an image signal in which a subject is imaged to imageprocessor 111 included in camera control unit 110 via video transmissioncable 117. In image processor 111, image processing is performed asappropriate after the inputted image signal is converted into imagedata, and desired image information for output is generated. Then, theobtained image information is displayed on a display, which is notillustrated, via controller 112, as an examination image of anendoscope. In addition, controller 112 stores, as necessary, the imageinformation in storage 113 which includes a memory, or the like.

[Operation]

In such light-emitting device 1, secondary light emitted from excitationlight source 3 enters first light-guiding member 50, is guided throughthe inside of first light-guiding member 50, exits from exit face 52 offirst light-guiding member 50, and enters NA converting member 73 ofconnector 70. The secondary light that entered NA converting member 73penetrates through NA converting member 73, exits from NA convertingmember 73, and enters entrance face 61 of second light-guiding member60. Then, the secondary light enters second light-guiding member 60, isguided through the inside of second light-guiding member 60, is guidedto exit face 62 of second light-guiding member 60 which is disposed inend portion 115, and exits from exit face 62 of second light-guidingmember 60. In this way, a subject can be illuminated by the secondarylight that is emitted on the subject. Accordingly, it is possible tounderstand a state of the subject by camera 116 imaging the subject onwhich the secondary light is emitted.

Advantageous Effect

Next, advantageous effects which light-emitting device 1 according tothe embodiment demonstrate will be described.

As has been described above, light-emitting device 1 according to theembodiment includes: laser light source 32 (solid-state light-emittingelement) that radiates blue-based light as primary light; wavelengthconverting member 36 that emits secondary light, the secondary lightincluding wavelength-converted light, the wavelength-converted lightbeing the primary light converted into light having more long-wavelengthcomponents than the primary light; first light-guiding member 50 thattransmits the secondary light emitted by wavelength converting member36; and second light-guiding member 60 which includes a resin material,and transmits the secondary light transmitted by first light-guidingmember 50. First light-guiding member 50 and second light-guiding member60 are connected by connector 70. Connector 70 incudes NA convertingmember 73 that optically connects a transmission path in firstlight-guiding member 50 and a transmission path in second light-guidingmember 60.

With this, a rise in cost of manufacturing second light-guiding member60 can be reduced, compared to a case in which second light-guidingmember 60 includes an expensive material such as glass fiber yarn.

In addition, since the secondary light enters second light-guidingmember 60 via first light-guiding member 50, second light-guiding member60 is provided apart from laser light source 32. For this reason, secondlight-guiding member 60 can reduce an effect of heat produced by laserlight source 32 that is a heat generation source.

Therefore, in light-emitting device 1, it is possible to reduce aneffect of heat produced by the heat generation source while reducing arise in cost.

Particularly, when light-emitting device 1 is used for an endoscope,second light-guiding member 60 is desired to be disposable forpreventing infectious diseases since second light-guiding member 60 isinserted in, for example, a human body. For this reason, light-emittingdevice 1 according to the embodiment is suitable for an endoscope.

In addition, in light-emitting device 1 according to the embodiment, thetransmission path of the secondary light in second light-guiding member60 has a diameter greater than a diameter of the transmission path ofthe secondary light in first light-guiding member 50.

With this, it is possible to cause the secondary light that is guidedthrough first light-guiding member 50 to efficiently enter secondlight-guiding member 60. For this reason, it is possible to reduce adecrease in the light transmission efficiency in connector 70, that is acomponent optically connecting first light-guiding member 50 and secondlight-guiding member 60.

In addition, in light-emitting device 1 according to the embodiment,second light-guiding member 60 includes light distribution controlstructure 60 a for performing light distribution control on thesecondary light transmitted by first light-guiding member 50 beforeemitting the secondary light.

With this, when camera 116 is disposed in the vicinity of lightdistribution control structure 60 a, the secondary light exited fromsecond light-guiding member 60 can be adjusted to an angle of view ofcamera 116, by preparing light distribution control structure 60 a to beadjusted to the angle of view of camera 116. For this reason, it ispossible to reduce narrowing of the field of view of camera 116.

In addition, in light-emitting device 1 according to the embodiment,light distribution control structure 60 a has a hemispherical shape.

With this, second light-guiding member 60 can emit, by simply changingcurvature of light distribution control structure 60 a, light on whichlight distribution control is performed according to an angle of view ofcamera 116.

In addition, in light-emitting device 1 according to the embodiment, NAconverting member 73 is disposed between exit face 52 of firstlight-guiding member 50 and entrance face 61 of second light-guidingmember 60, and supported by connector 70 in an orientation in which thesecondary light exited from exit face 52 of first light-guiding member50 is caused to enter entrance face 61 of second light-guiding member60.

With this, NA converting member 73 can cause the secondary light exitedfrom first light-guiding member 50 to stably enter second light-guidingmember 60. For this reason, it is possible to more reliably reduce adecrease in light transmission efficiency in connector 70 that opticallyconnects first light-guiding member 50 and second light-guiding member60.

In addition, in light-emitting device 1 according to the embodiment,connector 70 further includes case 71 that houses NA converting member73. Case 71 has a tubular body shape having unclosed ends, and thesecondary light passes through an inside of case 71. First light-guidingmember 50 is inserted in one end of case 71, and is removably fixed tocase 71. Second light-guiding member 60 is inserted in the other end ofcase 71, and is removably fixed to case 71.

Furthermore, light-emitting device 1 according to the embodiment furtherincludes: ferrule 151 (first ferrule) attached on an exit face 52 sideof first light-guiding member 50; and ferrule 161 (second ferrule)attached on an entrance face 61 side of second light-guiding member 60.In addition, first light-guiding member 50 and ferrule 151 are fixed tothe one end of case 71, and second light-guiding member 60 and ferrule161 are fixed to the other end of case 71.

Variation

The present disclosure has been described according to the embodiments,yet the present disclosure is not limited to such embodiments.

For example, in the light-emitting device according to the embodiments,the excitation light source need not include the prism, the condenserlens, the first glass rod, the wavelength converting member, and thesecond glass rod. Furthermore, the excitation light source need nothouse, in the case, the prism, the condenser lens, the first glass rod,the wavelength converting member, and the second glass rod. The prism,the condenser lens, the first glass rod, the wavelength convertingmember, and the second glass rod are not essential structural elementsof the excitation light source.

The present disclosure also encompasses: embodiments achieved byapplying various modifications conceivable to those skilled in the artto each embodiment; and embodiments achieved by optionally combining thestructural elements and the functions of each embodiment withoutdeparting from the essence of the present disclosure.

While the foregoing has described one or more embodiments and/or otherexamples, it is understood that various modifications may be madetherein and that the subject matter disclosed herein may be implementedin various forms and examples, and that they may be applied in numerousapplications, only some of which have been described herein. It isintended by the following claims to claim any and all modifications andvariations that fall within the true scope of the present teachings.

The invention claimed is:
 1. A light-emitting device, comprising: asolid-state light-emitting element that radiates blue-based light asprimary light; a wavelength converting member that emits secondarylight, the secondary light including wavelength-converted light, thewavelength-converted light being the primary light converted into lighthaving more long-wavelength components than the primary light; a firstlight-guiding member that transmits the secondary light emitted by thewavelength converting member; and a second light-guiding member whichincludes a resin material, and transmits the secondary light transmittedby the first light-guiding member, wherein the first light-guidingmember and the second light-guiding member are connected by a connector,the connector including a numerical aperture (NA) converting member thatoptically connects a transmission path in the first light-guiding memberand a transmission path in the second light-guiding member.
 2. Thelight-emitting device according to claim 1, wherein the transmissionpath of the secondary light in the second light-guiding member has adiameter greater than a diameter of the transmission path of thesecondary light in the first light-guiding member.
 3. The light-emittingdevice according to claim 1, wherein the second light-guiding memberincludes a light distribution control structure for performing lightdistribution control on the secondary light transmitted by the firstlight-guiding member before emitting the secondary light.
 4. Thelight-emitting device according to claim 3, wherein the lightdistribution control structure has a hemispherical shape.
 5. Thelight-emitting device according to claim 1, wherein the NA convertingmember is: disposed between an exit face of the first light-guidingmember and an entrance face of the second light-guiding member, andsupported by the connector in an orientation in which the secondarylight exited from the exit face of the first light-guiding member iscaused to enter the entrance face of the second light-guiding member. 6.The light-emitting device according to claim 1, wherein the connectorfurther includes a case that houses the NA converting member, the casehas a tubular body shape having unclosed ends, and the secondary lightpasses through an inside of the case, the first light-guiding member isinserted in one end of the case, and is removably fixed to the case, andthe second light-guiding member is inserted in an other end of the case,and is removably fixed to the case.
 7. The light-emitting deviceaccording to claim 6 further comprising: a first ferrule attached on anexit face side of the first light-guiding member; and a second ferruleattached on an entrance face side of the second light-guiding member,wherein the first light-guiding member and the first ferrule are fixedto the one end of the case, and the second light-guiding member and thesecond ferrule are fixed to the other end of the case.